signal.c File Reference

#include "uv.h"
#include "internal.h"
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

Go to the source code of this file.

Classes
struct	uv__signal_msg_t

Macros
#define	SA_RESTART   0

Functions
	RB_HEAD (uv__signal_tree_s, uv_signal_s)
static int	uv__signal_unlock (void)
static int	uv__signal_start (uv_signal_t *handle, uv_signal_cb signal_cb, int signum, int oneshot)
static void	uv__signal_event (uv_loop_t *loop, uv__io_t *w, unsigned int events)
static int	uv__signal_compare (uv_signal_t *w1, uv_signal_t *w2)
static void	uv__signal_stop (uv_signal_t *handle)
static void	uv__signal_unregister_handler (int signum)
	RB_GENERATE_STATIC (uv__signal_tree_s, uv_signal_s, tree_entry, uv__signal_compare)
void	uv__signal_cleanup (void)
static void	uv__signal_global_reinit (void)
void	uv__signal_global_once_init (void)
static int	uv__signal_lock (void)
static void	uv__signal_block_and_lock (sigset_t *saved_sigmask)
static void	uv__signal_unlock_and_unblock (sigset_t *saved_sigmask)
static uv_signal_t *	uv__signal_first_handle (int signum)
static void	uv__signal_handler (int signum)
static int	uv__signal_register_handler (int signum, int oneshot)
static int	uv__signal_loop_once_init (uv_loop_t *loop)
int	uv__signal_loop_fork (uv_loop_t *loop)
void	uv__signal_loop_cleanup (uv_loop_t *loop)
int	uv_signal_init (uv_loop_t *loop, uv_signal_t *handle)
void	uv__signal_close (uv_signal_t *handle)
int	uv_signal_start (uv_signal_t *handle, uv_signal_cb signal_cb, int signum)
int	uv_signal_start_oneshot (uv_signal_t *handle, uv_signal_cb signal_cb, int signum)
int	uv_signal_stop (uv_signal_t *handle)

Variables
static uv_once_t	uv__signal_global_init_guard = UV_ONCE_INIT
static struct uv__signal_tree_s	uv__signal_tree
static int	uv__signal_lock_pipefd [2] = { -1, -1 }

Macro Definition Documentation

SA_RESTART

#define SA_RESTART   0

Definition at line 32 of file signal.c.

Function Documentation

RB_GENERATE_STATIC()

RB_GENERATE_STATIC	(	uv__signal_tree_s	,
		uv_signal_s	,
		tree_entry	,
		uv__signal_compare
	)

Definition at line 59 of file signal.c.

                                         {
  if (uv__signal_lock_pipefd[0] == -1)
    /* pthread_atfork can register before and after handlers, one
     * for each child. This only registers one for the child. That
     * state is both persistent and cumulative, so if we keep doing
     * it the handler functions will be called multiple times. Thus
     * we only want to do it once.
     */
    if (pthread_atfork(NULL, NULL, &uv__signal_global_reinit))
      abort();
 
  uv__signal_global_reinit();
}

RB_HEAD()

RB_HEAD	(	uv__signal_tree_s	,
		uv_signal_s
	)

uv__signal_block_and_lock()

static void uv__signal_block_and_lock ( sigset_t *  saved_sigmask )

static

Definition at line 140 of file signal.c.

                                                               {
  sigset_t new_mask;
 
  if (sigfillset(&new_mask))
    abort();
 
  /* to shut up valgrind */
  sigemptyset(saved_sigmask);
  if (pthread_sigmask(SIG_SETMASK, &new_mask, saved_sigmask))
    abort();
 
  if (uv__signal_lock())
    abort();
}

References uv__signal_lock().

Referenced by uv__signal_start(), and uv__signal_stop().

uv__signal_cleanup()

void uv__signal_cleanup

(

void

)

Definition at line 80 of file signal.c.

                              {
  /* We can only use signal-safe functions here.
   * That includes read/write and close, fortunately.
   * We do all of this directly here instead of resetting
   * uv__signal_global_init_guard because
   * uv__signal_global_once_init is only called from uv_loop_init
   * and this needs to function in existing loops.
   */
  if (uv__signal_lock_pipefd[0] != -1) {
    uv__close(uv__signal_lock_pipefd[0]);
    uv__signal_lock_pipefd[0] = -1;
  }
 
  if (uv__signal_lock_pipefd[1] != -1) {
    uv__close(uv__signal_lock_pipefd[1]);
    uv__signal_lock_pipefd[1] = -1;
  }
}

References uv__close(), and uv__signal_lock_pipefd.

Referenced by uv__signal_global_reinit(), and uv_library_shutdown().

uv__signal_close()

void uv__signal_close

(

uv_signal_t *

handle

)

Definition at line 335 of file signal.c.

                                           {
  uv__signal_stop(handle);
}

References handle, and uv__signal_stop().

Referenced by uv_close().

uv__signal_compare()

static int uv__signal_compare ( uv_signal_t *  w1, uv_signal_t *  w2  )

static

Definition at line 483 of file signal.c.

                                                                {
  int f1;
  int f2;
  /* Compare signums first so all watchers with the same signnum end up
   * adjacent.
   */
  if (w1->signum < w2->signum) return -1;
  if (w1->signum > w2->signum) return 1;
 
  /* Handlers without UV_SIGNAL_ONE_SHOT set will come first, so if the first
   * handler returned is a one-shot handler, the rest will be too.
   */
  f1 = w1->flags & UV_SIGNAL_ONE_SHOT;
  f2 = w2->flags & UV_SIGNAL_ONE_SHOT;
  if (f1 < f2) return -1;
  if (f1 > f2) return 1;
 
  /* Sort by loop pointer, so we can easily look up the first item after
   * { .signum = x, .loop = NULL }.
   */
  if (w1->loop < w2->loop) return -1;
  if (w1->loop > w2->loop) return 1;
 
  if (w1 < w2) return -1;
  if (w1 > w2) return 1;
 
  return 0;
}

References f1, autogen_x86imm::f2, UV_SIGNAL_ONE_SHOT, w1, and w2.

uv__signal_event()

static void uv__signal_event ( uv_loop_t *  loop, uv__io_t *  w, unsigned int  events  )

static

Definition at line 416 of file signal.c.

                                                  {
  uv__signal_msg_t* msg;
  uv_signal_t* handle;
  char buf[sizeof(uv__signal_msg_t) * 32];
  size_t bytes, end, i;
  int r;
 
  bytes = 0;
  end = 0;
 
  do {
    r = read(loop->signal_pipefd[0], buf + bytes, sizeof(buf) - bytes);
 
    if (r == -1 && errno == EINTR)
      continue;
 
    if (r == -1 && (errno == EAGAIN || errno == EWOULDBLOCK)) {
      /* If there are bytes in the buffer already (which really is extremely
       * unlikely if possible at all) we can't exit the function here. We'll
       * spin until more bytes are read instead.
       */
      if (bytes > 0)
        continue;
 
      /* Otherwise, there was nothing there. */
      return;
    }
 
    /* Other errors really should never happen. */
    if (r == -1)
      abort();
 
    bytes += r;
 
    /* `end` is rounded down to a multiple of sizeof(uv__signal_msg_t). */
    end = (bytes / sizeof(uv__signal_msg_t)) * sizeof(uv__signal_msg_t);
 
    for (i = 0; i < end; i += sizeof(uv__signal_msg_t)) {
      msg = (uv__signal_msg_t*) (buf + i);
      handle = msg->handle;
 
      if (msg->signum == handle->signum) {
        assert(!(handle->flags & UV_HANDLE_CLOSING));
        handle->signal_cb(handle, handle->signum);
      }
 
      handle->dispatched_signals++;
 
      if (handle->flags & UV_SIGNAL_ONE_SHOT)
        uv__signal_stop(handle);
    }
 
    bytes -= end;
 
    /* If there are any "partial" messages left, move them to the start of the
     * the buffer, and spin. This should not happen.
     */
    if (bytes) {
      memmove(buf, buf + end, bytes);
      continue;
    }
  } while (end == sizeof buf);
}

References assert(), bytes, EAGAIN, EINTR, test_evm::end, handle, i, loop, msg, r, read(), uv__signal_stop(), UV_HANDLE_CLOSING, and UV_SIGNAL_ONE_SHOT.

Referenced by uv__signal_loop_once_init().

uv__signal_first_handle()

static uv_signal_t* uv__signal_first_handle ( int  signum )

static

Definition at line 165 of file signal.c.

                                                        {
  /* This function must be called with the signal lock held. */
  uv_signal_t lookup;
  uv_signal_t* handle;
 
  lookup.signum = signum;
  lookup.flags = 0;
  lookup.loop = NULL;
 
  handle = RB_NFIND(uv__signal_tree_s, &uv__signal_tree, &lookup);
 
  if (handle != NULL && handle->signum == signum)
    return handle;
 
  return NULL;
}

References handle, NULL, RB_NFIND, signum, uv_signal_s::signum, and uv__signal_tree.

Referenced by uv__signal_handler(), uv__signal_start(), and uv__signal_stop().

uv__signal_global_once_init()

void uv__signal_global_once_init

(

void

)

Definition at line 111 of file signal.c.

                                       {
  uv_once(&uv__signal_global_init_guard, uv__signal_global_init);
}

References uv__signal_global_init_guard, and uv_once().

Referenced by uv_loop_init().

uv__signal_global_reinit()

static void uv__signal_global_reinit ( void  )

static

Definition at line 100 of file signal.c.

                                           {
  uv__signal_cleanup();
 
  if (uv__make_pipe(uv__signal_lock_pipefd, 0))
    abort();
 
  if (uv__signal_unlock())
    abort();
}

References uv__make_pipe(), uv__signal_cleanup(), uv__signal_lock_pipefd, and uv__signal_unlock().

uv__signal_handler()

static void uv__signal_handler ( int  signum )

static

Definition at line 183 of file signal.c.

                                           {
  uv__signal_msg_t msg;
  uv_signal_t* handle;
  int saved_errno;
 
  saved_errno = errno;
  memset(&msg, 0, sizeof msg);
 
  if (uv__signal_lock()) {
    errno = saved_errno;
    return;
  }
 
  for (handle = uv__signal_first_handle(signum);
       handle != NULL && handle->signum == signum;
       handle = RB_NEXT(uv__signal_tree_s, &uv__signal_tree, handle)) {
    int r;
 
    msg.signum = signum;
    msg.handle = handle;
 
    /* write() should be atomic for small data chunks, so the entire message
     * should be written at once. In theory the pipe could become full, in
     * which case the user is out of luck.
     */
    do {
      r = write(handle->loop->signal_pipefd[1], &msg, sizeof msg);
    } while (r == -1 && errno == EINTR);
 
    assert(r == sizeof msg ||
           (r == -1 && (errno == EAGAIN || errno == EWOULDBLOCK)));
 
    if (r != -1)
      handle->caught_signals++;
  }
 
  uv__signal_unlock();
  errno = saved_errno;
}

References assert(), EAGAIN, EINTR, handle, memset(), msg, NULL, r, RB_NEXT, signum, uv__signal_first_handle(), uv__signal_lock(), uv__signal_tree, uv__signal_unlock(), and write.

Referenced by uv__signal_register_handler().

uv__signal_lock()

static int uv__signal_lock ( void  )

static

Definition at line 116 of file signal.c.

                                 {
  int r;
  char data;
 
  do {
    r = read(uv__signal_lock_pipefd[0], &data, sizeof data);
  } while (r < 0 && errno == EINTR);
 
  return (r < 0) ? -1 : 0;
}

References EINTR, r, read(), and uv__signal_lock_pipefd.

Referenced by uv__signal_block_and_lock(), and uv__signal_handler().

uv__signal_loop_cleanup()

void uv__signal_loop_cleanup

(

uv_loop_t *

loop

)

Definition at line 291 of file signal.c.

                                              {
  QUEUE* q;
 
  /* Stop all the signal watchers that are still attached to this loop. This
   * ensures that the (shared) signal tree doesn't contain any invalid entries
   * entries, and that signal handlers are removed when appropriate.
   * It's safe to use QUEUE_FOREACH here because the handles and the handle
   * queue are not modified by uv__signal_stop().
   */
  QUEUE_FOREACH(q, &loop->handle_queue) {
    uv_handle_t* handle = QUEUE_DATA(q, uv_handle_t, handle_queue);
 
    if (handle->type == UV_SIGNAL)
      uv__signal_stop((uv_signal_t*) handle);
  }
 
  if (loop->signal_pipefd[0] != -1) {
    uv__close(loop->signal_pipefd[0]);
    loop->signal_pipefd[0] = -1;
  }
 
  if (loop->signal_pipefd[1] != -1) {
    uv__close(loop->signal_pipefd[1]);
    loop->signal_pipefd[1] = -1;
  }
}

References handle, uv_loop_s::handle_queue, loop, QUEUE_DATA, QUEUE_FOREACH, uv__close(), and uv__signal_stop().

Referenced by uv__loop_close(), and uv_loop_init().

uv__signal_loop_fork()

int uv__signal_loop_fork

(

uv_loop_t *

loop

)

Definition at line 281 of file signal.c.

                                          {
  uv__io_stop(loop, &loop->signal_io_watcher, POLLIN);
  uv__close(loop->signal_pipefd[0]);
  uv__close(loop->signal_pipefd[1]);
  loop->signal_pipefd[0] = -1;
  loop->signal_pipefd[1] = -1;
  return uv__signal_loop_once_init(loop);
}

References loop, uv__close(), uv__io_stop(), and uv__signal_loop_once_init().

Referenced by uv_loop_fork().

uv__signal_loop_once_init()

static int uv__signal_loop_once_init ( uv_loop_t *  loop )

static

Definition at line 261 of file signal.c.

                                                      {
  int err;
 
  /* Return if already initialized. */
  if (loop->signal_pipefd[0] != -1)
    return 0;
 
  err = uv__make_pipe(loop->signal_pipefd, UV__F_NONBLOCK);
  if (err)
    return err;
 
  uv__io_init(&loop->signal_io_watcher,
              uv__signal_event,
              loop->signal_pipefd[0]);
  uv__io_start(loop, &loop->signal_io_watcher, POLLIN);
 
  return 0;
}

References err, loop, UV__F_NONBLOCK, uv__io_init(), uv__io_start(), uv__make_pipe(), and uv__signal_event().

Referenced by uv__signal_loop_fork(), and uv_signal_init().

uv__signal_register_handler()

static int uv__signal_register_handler ( int  signum, int  oneshot  )

static

Definition at line 224 of file signal.c.

                                                                {
  /* When this function is called, the signal lock must be held. */
  struct sigaction sa;
 
  /* XXX use a separate signal stack? */
  memset(&sa, 0, sizeof(sa));
  if (sigfillset(&sa.sa_mask))
    abort();
  sa.sa_handler = uv__signal_handler;
  sa.sa_flags = SA_RESTART;
  if (oneshot)
    sa.sa_flags |= SA_RESETHAND;
 
  /* XXX save old action so we can restore it later on? */
  if (sigaction(signum, &sa, NULL))
    return UV__ERR(errno);
 
  return 0;
}

References memset(), NULL, oneshot(), SA_RESTART, signum, UV__ERR, and uv__signal_handler().

Referenced by uv__signal_start(), and uv__signal_stop().

uv__signal_start()

static int uv__signal_start ( uv_signal_t *  handle, uv_signal_cb  signal_cb, int  signum, int  oneshot  )

static

Definition at line 352 of file signal.c.

                                         {
  sigset_t saved_sigmask;
  int err;
  uv_signal_t* first_handle;
 
  assert(!uv__is_closing(handle));
 
  /* If the user supplies signum == 0, then return an error already. If the
   * signum is otherwise invalid then uv__signal_register will find out
   * eventually.
   */
  if (signum == 0)
    return UV_EINVAL;
 
  /* Short circuit: if the signal watcher is already watching {signum} don't
   * go through the process of deregistering and registering the handler.
   * Additionally, this avoids pending signals getting lost in the small
   * time frame that handle->signum == 0.
   */
  if (signum == handle->signum) {
    handle->signal_cb = signal_cb;
    return 0;
  }
 
  /* If the signal handler was already active, stop it first. */
  if (handle->signum != 0) {
    uv__signal_stop(handle);
  }
 
  uv__signal_block_and_lock(&saved_sigmask);
 
  /* If at this point there are no active signal watchers for this signum (in
   * any of the loops), it's time to try and register a handler for it here.
   * Also in case there's only one-shot handlers and a regular handler comes in.
   */
  first_handle = uv__signal_first_handle(signum);
  if (first_handle == NULL ||
      (!oneshot && (first_handle->flags & UV_SIGNAL_ONE_SHOT))) {
    err = uv__signal_register_handler(signum, oneshot);
    if (err) {
      /* Registering the signal handler failed. Must be an invalid signal. */
      uv__signal_unlock_and_unblock(&saved_sigmask);
      return err;
    }
  }
 
  handle->signum = signum;
  if (oneshot)
    handle->flags |= UV_SIGNAL_ONE_SHOT;
 
  RB_INSERT(uv__signal_tree_s, &uv__signal_tree, handle);
 
  uv__signal_unlock_and_unblock(&saved_sigmask);
 
  handle->signal_cb = signal_cb;
  uv__handle_start(handle);
 
  return 0;
}

References assert(), err, handle, NULL, oneshot(), RB_INSERT, signum, uv__handle_start, uv__is_closing, uv__signal_block_and_lock(), uv__signal_first_handle(), uv__signal_register_handler(), uv__signal_stop(), uv__signal_tree, uv__signal_unlock_and_unblock(), and UV_SIGNAL_ONE_SHOT.

Referenced by uv_signal_start(), and uv_signal_start_oneshot().

uv__signal_stop()

static void uv__signal_stop ( uv_signal_t *  handle )

static

Definition at line 520 of file signal.c.

                                                 {
  uv_signal_t* removed_handle;
  sigset_t saved_sigmask;
  uv_signal_t* first_handle;
  int rem_oneshot;
  int first_oneshot;
  int ret;
 
  /* If the watcher wasn't started, this is a no-op. */
  if (handle->signum == 0)
    return;
 
  uv__signal_block_and_lock(&saved_sigmask);
 
  removed_handle = RB_REMOVE(uv__signal_tree_s, &uv__signal_tree, handle);
  assert(removed_handle == handle);
  (void) removed_handle;
 
  /* Check if there are other active signal watchers observing this signal. If
   * not, unregister the signal handler.
   */
  first_handle = uv__signal_first_handle(handle->signum);
  if (first_handle == NULL) {
    uv__signal_unregister_handler(handle->signum);
  } else {
    rem_oneshot = handle->flags & UV_SIGNAL_ONE_SHOT;
    first_oneshot = first_handle->flags & UV_SIGNAL_ONE_SHOT;
    if (first_oneshot && !rem_oneshot) {
      ret = uv__signal_register_handler(handle->signum, 1);
      assert(ret == 0);
      (void)ret;
    }
  }
 
  uv__signal_unlock_and_unblock(&saved_sigmask);
 
  handle->signum = 0;
  uv__handle_stop(handle);
}

References assert(), handle, NULL, RB_REMOVE, uv__handle_stop, uv__signal_block_and_lock(), uv__signal_first_handle(), uv__signal_register_handler(), uv__signal_tree, uv__signal_unlock_and_unblock(), uv__signal_unregister_handler(), and UV_SIGNAL_ONE_SHOT.

Referenced by uv__signal_close(), uv__signal_event(), uv__signal_loop_cleanup(), uv__signal_start(), and uv_signal_stop().

uv__signal_unlock()

static int uv__signal_unlock ( void  )

static

Definition at line 128 of file signal.c.

                                   {
  int r;
  char data = 42;
 
  do {
    r = write(uv__signal_lock_pipefd[1], &data, sizeof data);
  } while (r < 0 && errno == EINTR);
 
  return (r < 0) ? -1 : 0;
}

References EINTR, r, uv__signal_lock_pipefd, and write.

Referenced by uv__signal_global_reinit(), uv__signal_handler(), and uv__signal_unlock_and_unblock().

uv__signal_unlock_and_unblock()

static void uv__signal_unlock_and_unblock ( sigset_t *  saved_sigmask )

static

Definition at line 156 of file signal.c.

                                                                   {
  if (uv__signal_unlock())
    abort();
 
  if (pthread_sigmask(SIG_SETMASK, saved_sigmask, NULL))
    abort();
}

References NULL, and uv__signal_unlock().

Referenced by uv__signal_start(), and uv__signal_stop().

uv__signal_unregister_handler()

static void uv__signal_unregister_handler ( int  signum )

static

Definition at line 245 of file signal.c.

                                                      {
  /* When this function is called, the signal lock must be held. */
  struct sigaction sa;
 
  memset(&sa, 0, sizeof(sa));
  sa.sa_handler = SIG_DFL;
 
  /* sigaction can only fail with EINVAL or EFAULT; an attempt to deregister a
   * signal implies that it was successfully registered earlier, so EINVAL
   * should never happen.
   */
  if (sigaction(signum, &sa, NULL))
    abort();
}

References memset(), NULL, and signum.

Referenced by uv__signal_stop().

uv_signal_init()

int uv_signal_init	(	uv_loop_t *	loop,
		uv_signal_t *	handle
	)

Definition at line 319 of file signal.c.

                                                         {
  int err;
 
  err = uv__signal_loop_once_init(loop);
  if (err)
    return err;
 
  uv__handle_init(loop, (uv_handle_t*) handle, UV_SIGNAL);
  handle->signum = 0;
  handle->caught_signals = 0;
  handle->dispatched_signals = 0;
 
  return 0;
}

uv_signal_start()

int uv_signal_start	(	uv_signal_t *	handle,
		uv_signal_cb	signal_cb,
		int	signum
	)

Definition at line 340 of file signal.c.

                                                                             {
  return uv__signal_start(handle, signal_cb, signum, 0);
}

uv_signal_start_oneshot()

int uv_signal_start_oneshot	(	uv_signal_t *	handle,
		uv_signal_cb	signal_cb,
		int	signum
	)

Definition at line 345 of file signal.c.

                                        {
  return uv__signal_start(handle, signal_cb, signum, 1);
}

uv_signal_stop()

int uv_signal_stop

(

uv_signal_t *

handle

)

Definition at line 513 of file signal.c.

                                        {
  assert(!uv__is_closing(handle));
  uv__signal_stop(handle);
  return 0;
}

Referenced by uv__signal_start(), uv_process_signal_req(), and uv_signal_close().

Variable Documentation

uv__signal_global_init_guard

uv_once_t uv__signal_global_init_guard = UV_ONCE_INIT

static

Definition at line 54 of file signal.c.

Referenced by uv__signal_global_once_init().

uv__signal_lock_pipefd

int uv__signal_lock_pipefd[2] = { -1, -1 }

static

Definition at line 57 of file signal.c.

Referenced by uv__signal_cleanup(), uv__signal_global_reinit(), uv__signal_lock(), and uv__signal_unlock().

uv__signal_tree

struct uv__signal_tree_s uv__signal_tree

static

Initial value:

=
    RB_INITIALIZER(uv__signal_tree)

Definition at line 54 of file signal.c.

Referenced by uv__signal_first_handle(), uv__signal_handler(), uv__signal_start(), and uv__signal_stop().